Controls on the genesis of gold mineralisation in the Brucejack epithermal deposit, British Columbia

对不列颠哥伦比亚省布鲁斯杰克浅成热液矿床金矿化成因的控制

• 批准号: 543413-2019
• 负责人: WilliamsJones, Anthony
• 金额: $ 4.09万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=720707
• 关键词: Controls; genesis; gold; mineralisation; Brucejack

Some epithermal deposits are characterised by extraordinarily high metal concentrations of gold and silver, but despite their obvious attraction, they are difficult to explore and develop because zones of hyper-enrichment (bonanza zones) are commonly adjacent to barren zones. The Brucejack deposit in northern British Columbia, where Pretium Resources Inc. initiated mining in 2017, is an example of such a deposit. There, veins containing kilograms of Au/ton are accompanied by veins of the same generation that are devoid of gold (electrum). The reason why this and some other deposits contain these locally hyper-enriched gold-silver veins has not been satisfactorily explained. Indeed, it is difficult to understand how the fluids considered to be responsible for the formation of epithermal ore deposits could fill cm-wide fractures with gold for distances of several metres (the case at Brucejack) by simple precipitation, given that the gold content of these fluids has been shown to be on the order of 10's of ppb. An alternative hypothesis, which is suggested by preliminary high resolution transmitted electron microscope (HRTEM) images of gold-silver nano-particles (3-7 nm diameter) in samples from Brucejack, is that the gold/silver super-saturates as electrum nano-particles which subsequently flocculate, accumulate and then are mechanically transported into selected fractures, perhaps subsidiary to the major fluid conduits. We will test this hypothesis with further HRTEM imaging, EDS-assisted TEM analyses, and experiments designed to produce colloids and determine the controls on their flocculation. The bonanza gold mineralisation at Brucejack was preceded by auriferous arsenian pyrite that is developed locally within a five km-long corridor of phyllic alteration, possibly reflecting a porphyry system at depth, and contributes significantly to the resource and is closely associated with the electrum. The proposed research will develop a comprehensive model for the genesis of the Brucejack deposit that will explain the phyllic alteration, arsenian pyrite and bonanza-type electrum (and the links between them), consider the possibility of a telescoped epithermal-porphyry system, and help guide the ongoing exploration and mine development.

某些以使者的沉积物的特征是金属浓度非常高，但是尽管它们的吸引力明显，但它们还是很难探索和发展，因为高增强区（Bonanza区域）通常与贫瘠的区域相邻。不列颠哥伦比亚省北部的Brucejack押金是2017年启动采矿的Brucejack押金，是这种押金的一个例子。在那里，含有AU/吨的千克脉伴随着没有黄金（Electrum）的同一代人的静脉。尚未令人满意地解释这种局部和其他一些沉积物的原因。的确，很难理解如何通过简单的沉淀物填充几米（Brucejack的距离），如何用金填充cm范围的矿石沉积物的形成的流体，鉴于这些流体的黄金含量已显示为PPB的10个顺序。 An alternative hypothesis, which is suggested by preliminary high resolution transmitted electron microscope (HRTEM) images of gold-silver nano-particles (3-7 nm diameter) in samples from Brucejack, is that the gold/silver super-saturates as electrum nano-particles which subsequently flocculate, accumulate and then are mechanically transported into selected fractures, perhaps subsidiary to the major fluid导管。我们将通过进一步的HRTEM成像，EDS辅助TEM分析和旨在产生胶体的实验来检验该假设，并确定其絮凝的对照。 Brucejack处的Bonanza Gold矿化之前是在五年级的阳极变化的五公里长的走廊内在本地开发的Auriferis Arsenian黄铁矿，可能会在深度上反映斑岩系统，并对资源产生了重大贡献，并与电子紧密相关。拟议的研究将开发一个用于Brucejack沉积物的起源的综合模型，该模型将解释纤利的改变，阿森尼亚黄铁矿和bonanza型电子（以及它们之间的链接），考虑到望远镜上皮孢子型系统的可能性，并有助于指导正在进行的勘探和正在进行的勘探和矿山的开发。